Re: Zero Packets in Isochronous Transfer Reception

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On Sun, Jul 1, 2018 at 9:12 AM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> On Sat, 30 Jun 2018, R0b0t1 wrote:
>
>> The problem seems more noticeable when using the Python libusb
>> bindings but it still exists when using libusb directly. Can anyone
>> suggest what to look into?
>
> Have you tried using usbmon to capture the data as it is received by
> the kernel?
>

Thank you for the suggestion. Having looked at usbmon output it
appears the kernel is receiving all zero packets for some transfers.
It also looks like some packets are dropped, but I am not sure how to
tell. Are blank transfers dropped data also?

If I try to reconstitute the audio stream by ignoring all zero packets
the stream still experiences pops and clicks though they are much
quieter. That is the best indication I have that packets are being
dropped. The discontinuities in the waves lead to the pops and clicks.

Cheers,
     R0b0t1
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